NTSB Probable Cause

THE PILOT'S INADVERTENT FLIGHT INTO A MOUNTAINOUS AREA WHERE HE LOST VISUAL REFERENCE TO ILLUMINATED GROUND FEATURES WHICH RESULTED IN HIS BECOMING DISORIENTED. FACTORS WHICH CONTRIBUTED TO THE ACCIDENT WERE: 1) THE DARK SKY AND LOW CLOUD CONDITIONS; 2) THE PILOT'S FAILURE TO OBTAIN A COMPLETE WEATHER BRIEFING PRIOR TO TAKE OFF; 3) HIS IMPROPER WEATHER EVALUATION; 4) HIS INEXPERIENCE FLYING AT NIGHT; AND 5) THE USAF'S CLEARING AUTHORITY PERSONNEL'S FAILURE TO ADHERE TO ESTABLISHED WRITTEN PROCEDURES WHICH BARRED INEXPERIENCED PILOTS FROM BEING DISPATCHED WITH THE INTENT OF PERFORMING NIGHTTIME CROSS COUNTRY FLIGHTS.